Organic light-emitting devices (OLEDs) are a kind of display device different from conventional liquid crystal displays (LCDs). OLEDs have advantages of active light emission, good temperature characteristic, low power consumption, rapid response, being bendable, being ultra-light and ultra-thin, low cost and the like, and thus, they have become one of important developments and findings of the new generation display devices, and have attracted more and more attentions.
OLED display substrates can be classified into the following three types depending on the light output direction: a bottom emitting type OLED, a top emitting type OLED, and a double-side emitting type OLED. Here, the bottom emitting type OLED refers to an OLED in which a light is emitted from the substrate side. Further, the double-side emitting type OLED refers to an OLED in which lights are emitted from both surfaces of the OLED.